Method and system of signal path tracking

Abstract

A signal path tracking method and system for symbol timing recovery. In digital communication, a receiver requires a symbol sampler and a match filter to digitalize analog signals. The symbol sampler establishes on-time samples according to preset current sampling points. The present invention provides a method to improve synchronization between the receiver and the received signal by comparing the current sampling points with acquisition of maximum signal strength. The moving average of the timing difference is used to predict expected errors for future sampling points. The timing scheme is then adjusted according to the expected errors in order to generate future sampling points for sampling subsequent symbols precisely, thereby recovering the synchronization.

1 . A method of signal path tracking for symbol timing recovery in a receiver, comprising the steps of: 
 providing current sampling points for a received signal to generate current symbols according to a timing scheme;    detecting optimal points of the current symbols for sampling the received signal;    computing an expected error from the current sampling points and the optimal points; and    adjusting the timing scheme to generate a future sampling point for a subsequent symbol according to the expected error, thereby recovering symbol timing of the receiver.    
   
   
       2 . The method according to  claim 1 , wherein computing the expected error further comprises: 
 comparing the current sampling points with the optimal points to obtain timing differences;    filtering the timing differences to obtain an average moving error; and    integrating the average moving error to obtain the expected error.    
   
   
       3 . The method according to  claim 2 , wherein filtering the timing differences further comprises convolution and accumulation of the timing differences.  
   
   
       4 . The method according to  claim 1 , wherein the optimal points for sampling the received signal correspond with samplings of a maximum signal strength in each symbol duration.  
   
   
       5 . The method according to  claim 1 , wherein computation of the expected error occurs once every N symbols, and the current sampling points and the optimal points for computing the expected error are averages of the N current symbols.  
   
   
       6 . The method according to  claim 1 , wherein the timing scheme for sampling the received signal is adjusted to continue alignment of a sampling clock transition with an optimal sampling point computed by the expected error of a preceding symbol.  
   
   
       7 . A system of signal path tracking for symbol timing recovery in a receiver comprising: 
 a symbol sampler, sampling a received signal at current sampling point according to a timing scheme;    a peak detector, detecting optimal points for sampling the received signal;    an error detector, computing an expected error from the optimal points detected by the peak detector and the current sampling points of the symbol sampler; and    a path tracker, computing a future sampling point of a subsequent symbol and providing the future sampling point to the symbol sampler to adjust the timing scheme.    
   
   
       8 . The system for symbol timing recovery according to  claim 7 , the error detector further comprising: 
 a comparator, comparing the current sampling points of the symbol sampler and the optimal points detected by the peak detector to obtain timing differences;    a loop filter, filtering the timing differences received from the comparator to obtain an average moving error; and    an integrator, integrating the average moving error from the loop filter to obtain an expected error.    
   
   
       9 . The system for symbol timing recovery according to  claim 7 , wherein the optimal points for sampling the received signal correspond with samplings of a maximum signal strength in each symbol duration.  
   
   
       10 . The system for symbol timing recovery according to  claim 7 , wherein the error detector computes the expected error once every N symbols, and the current sampling points and the optimal points for computing the expected error are averages of N symbols.